This invention relates generally to combustion systems and more particularly, to methods and systems to facilitate reducing flashback/flame holding in combustion systems.
During the combustion of natural gas and liquid fuels, known lean-premixed combustors generally experience flame holding or flashback in which a pilot flame that is intended to be confined within the combustion liner travels upstream towards the injection locations of fuel and air into the combustion liner. Generally, uniform lean fuel-air mixtures, lower flame temperatures, and/or shorter residence burning time are known to reduce formation of local near stoichiometric zones and lower flow velocity regions in which flashback may occur. At least some known gas turbine combustion systems include premixing injectors that premix fuel and compressed airflow in attempts to channel uniform lean fuel-air premixtures to a combustion liner.
Generally, at least some known premixing injectors include an inlet flow conditioner that conditions compressed airflow in attempts to obtain a substantially uniform airflow to mix with fuel. Such known injectors also generally include a burner tube that channels a fuel-air mixture to a combustor. Non-uniform fuel-air concentrations within the burner tube may enable flame holding or flashback conditions such that a pilot flame that is intended to be confined within the combustion liner travels into the premixing injector. As a result, such injectors may be damaged and/or the operability of the combustor may be compromised.